Cam follower construction



. Aug. 31, 1948. l. clssKl 2,448,355

CAM FoLLowER coNsTRUcTIQN l Filed Aug. 2, 1946 2 Sheets-Sheet 1 0 @y A a5 Allg 31, 1948 i. lsskl 2,448,355

CAM FOLLOWER CONSTRUCTION Filed Aug. 2, 1946 2 Sheets-Sheet 2 Patented Aug. 31, 1948 CAM FLJOWER CONSTRUCTION Irving Cisski, Schiller Park, Ill., assignor to Ampro Corporation, Chicago, Ill., a corporation of Illinois 7 Claims.- 1

This invention relates to cam track construction for film-shutter and transport mechanism, of the type which employs cams for reciprocating blades mounted in closely-spaced parallel planes and adapted to 'actuatershutters and a claw for respectively exposing the lm and adadvancing it after exposure, in either cameras or projectors. The use of cinematograph, hereafter in thisv specication, is to be understood to embrace both cameras and projectors, notwithstanding the fact that the invention is shown as applied to a mechanism for cameras.`

In cameras constructed for use with a -lm encased in a magazine by the nlm manufacturer, for return to it for processing,v the aim is to reduce as much as possible theover-all dimensions of the camera. Moreover, lens mounts for 16 mm. motion picture cameras are constructed to accommodate an accepted standard lens-seat reg istration distance; i. e., the distance from the lens seat to thev film. Therefore, the space between the lens-mount support and the plate, for the support of the film-shutter and transport mechanism is limit-ed. This space is further limited if a lens turret isA employed to permit ready changing of lenses. An improved form of cam-actuated, parallel-reciprocating, blades has been developed as mechanism particularly suitable for actuating thelm-exposing shutters and the nlm-transport claw within this' confined space. One of the sp-ecial features of this improved mechanism is an improved construction of a cam track. An improved nlm-shutter and transport mechanism of this type, and with which an improved cam track construction has been incorporated, is shown' in co-pendi'ng application Serial No. 640,952, led January 12, 1946.

The main objects of this invention,A therefore, are to provide an improved form of cam track, for nlm-shutter and transport mechanism of the above-mentioned type, adapted to presenta bearing surface for the operating cam;` to provide an improved interfitting construction for said cam track and the blades of this type of mechanism, which iirmly secures the cam track in position in the plane of the blade and` permits easy as sembly and separation; and. to provide a cam track construction of' this kind which permits the very thin blades, of the type above-mentioned, to be very compactly mounted in a very restricted operating space.

A preferred' embodiment of. this irwentionis` shown inthe accompanying drawings on a scale somewhat larger than actual size, whereinf Fig. 1 is a front elevation of a camera housing 2 with the front closure plate cut away and showing a filmt-shutter and transport mechanism, ci the type disclosed in the hereinbefore-mentioned application, which includes a cam track construction embodying this invention;

Fig. 2` is a vertical sectional view of the same taken on the line 2-'2 of Fig. 1 but showing the front closure plate in position;

Fig. 3 is a side elevation of the lower end of one of the blades employed in a film-shutter and transport mechanism, of the illustrated type, with the cam track removed;

Fig. l is a similar View but showing the cam track member in the process of being assembled with or removed from the blade;

Fig. 5 is a transverse cross-sectional view of the blade shown in Fig. 3, as viewed from the plane of the line 55';

Fig. 6 is an edge View of the cam track member; and

Fig. 7 is a vertical sectional View of the partial assembly shown in Fig. 4 as viewed from the plane of line 1'l.

A motion picture camera constructed to incorporate a nlm-shutter and transport mechanism including this improved type of cam track construction, comprises a compartment 20 formed between the camera, housing parts 2l and 2-2 wherein is mounted a pair of film-shutter blades 23 and 24 and a nlm-transport blade 25 which are adapted to be reciprocated in their respective planes by means of film-shutter cams 26 and 21 and a nlm-transport cam 28 all mountedon a shaft "29. The shaft 29 is driven through suitable gearing by a spring motor (not shown), so that a lm 30 is intermittently advanced for recurring exposure as apertures in the shutter blades 23 and 24 are brought into registration.

The housing part 2i is a plate forming a closure for the front end Aof the cinematograph housing 3l and provides a support for the operating and guide parts of the film-shutter and transport mechanism, The housing` part 22 is in the form of an end cap secured to the main housing part 3i by means of screws 32 with the shutter-mechanism plate 2| clamped between the intei'tti'ng anges 33 and (i4.

The -space between the opposed' faces of these two parts is practically a quarter of an inch. This is the maximum that can be provided between the parts of the housing one of which af-A fords support for a lens seat 35 of :a turrent lensmount support so and the other of which provides support for light baffle 3i. Such a limitation in the space, between the plate 21 and' cap 3 22, grows out of the fact that the lens seat 35 must be located a predetermined distance from the focal plane coincident with the path of the lm 30.

The plate 2i has the light baffle 31 secured in axial registration, with a light baffle 38 formed on the end cap 22 co-axially of the lens-mount support 36. As will be noted, the lens-mount support 35 is provided with internal threads 30 to receive corresponding threads on a lens mount (not shown) adapted to abut against the lens seat 35 to locate the lens the aforesaid predetermined distance from the focal plane through which the film 3d moves.

The shutter-mechanism plate 2i also has a slot [iii formed therein through which protrudes the claw lil mounted on the film-transport blade 25. Such a claw is adapted to engage the conventional perforations in the iilm 30 for advancing the film. A button 42, secured on the shutter-mechanism plate 2 l, serve as a gauge to properly position a nlm magazine to locate the film 30 therein the proper focal distance from the lens seat 35. Adjacent to its base, the plate 2l has an annulus i3 mounted thereon which provides :a support for the ball bearing 4d for the cam shaft 29, the end of which extends into an alined opening 45 in the end cap 22,

The nlm-shutter and transport blades 23, 24, and 25 are form-ed of thin blue tempered steel sheets of about .007" thick. At their lower ends each of these blades is provided with an oblongshaped opening 4e to permit the insertion of a cam track 41. The horizontally-opposed perimeters of these openings are parallel and provide surfaces 46 against which the cam track 41 rests. Intermediate these surfaces 46 are formed flexible Opposed side portions provided with arcuate-shaped flanges or shoulders 45 projecting into the opening d5 and which engage grooves in the cam track 41. At their upper ends these blades are recessed at 48 and 49 to receive the respective guides 50 and 5i. These upper guides co-act with guides 52, formed on ears 53 struck 11p-from the shutter-mechanism plate 2i, to retain the blades against lateral movement in their respective planes during their reciprocal move-, ment.

As will be most clearly observed from Fig. 2, the film-shutter blades 25 and 24 are offset forwardly of the end cap 22 so as to locate their apertured parts in the narrow space between the light baffles 31 and 38. At this point the blades are spaced about .007 apart, so as to prevent the leakage of light through the baflles. Filmexposure apertures 54 and 55 are formed in these portions of the plates 23 and 24 and, as will appear more fully hereinafter, under the action of the cams 2t and 21, are moved into and out of registering alinement with the optical centerline 55, for successively exposing the lm Sie to and concealing it from light rays through the lens on the lens-mount support 36.

The guide 50 for the upper ends of the blades 23 and 24 comprises a roller on a hub 51 which supports a spring-pressed pin 58 forming a part of the lens-turret locking mechanism which is the subject matter of a co-pending application.

As will appear more clearly from Fig. l, the nlm-transport blade 25 has a part 59 offset from the claw 4l. In this offset is formed the slot 49 embracing the guide block 5l mounted on a pin supported on the shutter-mechanism plate 2i and the end cap 22.

The transport blade 25 is bent inwardly slightly 4 so as to have a tendency to force the claw 4l toward the nim S0, thereby ensuring the engagement of the point of the claw with the perforation in the nlm. The claw 4l is of the slip type. The lower edge thereof has a rake" angle of approximately 2 so as to ensure against disengagement of the claw from the film perforation while the claw is transporting the nlm.

The cam tracks 41 are in the form of oblong frames considerably thicker than the blades 23, 24, and 25, the tracks being approximately .028 whereas the blades are .007. These cam tracks are of'oblong shape similar to the blade openings 46,thus providing upper and lower parallel surfaces Gi) and 6| against which the respective cams 25, 21, andv 28 bear. Intermediate the perimetrical portions parallel to the surfaces 60 and 5i, the cam tracks are rounded to permit clearance of the cams. The resultant movement ofthe blades 23, 24, and 25 is reciprocation in a vertical plane. The arcuate portions of each cam track are recessed at 62 to receive the flanges or projections 46" of the respective blades 23, 24, and 2-5.

By virtue of the particular form of these camfore the inertia forces of the shutter blades 23 and 24 are always in balance. This materially reduces, if it does not eliminate, vibrationA incident to their operation. The cams 26, 21, and

28 are held in their assembled relationship on a cam hub 63 by a cam nut 38 screwed onto the end of the drive shaft 29, which shaft is fixed to rotate with a triggerA cam 69.v The cam hub 63 is formed to fit on the shaft 29 and carry one part of the ball bearing 44.

Variations and modifications of thedetails of structure and arrangement of the parts herein shown and described may be resorted to within the spirit and coverage of the appended claims.

I claim:

1. A device of the class described comprising, a blade of extremely thin flexible material having an opening formed therein, and a member of greater thickness than said blade providing opposed cam surfaces and shaped to fit in said blade opening in the plane of said blade with the perimetrical edges of said member bearing against opposite perimetricaledges of said blade, said member having grooves formed in opposite peripheral portions thereof, and shoulders on cor-- responding peripheral portions of said blade adapted to t in said' grooves for locking said member in pla-ce in said bladeopening, said shoulders being adapted to enter into or recede from said grooves when said blade intermediate said -shoulders is flexed to dispose such portions out of the normal plane of said blade and said member and blade are givenr a relative partial rotative movement.

2. A device of the class described comprising, a blade of extremely thin flexible material having an oblong opening formed therein so as to provide opposed parallel'cam-track bearing surfaces and opposed arcuate shaped projections, and a cam track member of substantially the same shape as said blade opening and of materially greater thickness than said blade adapted to t in said blade opening with opposite perimetrical edges abutting said opposed parallel blade surfaces, said member intermediate said parallel surfaces being of the same arcuate shape as said opposed arcuate projections of said blade opening intermediate said cam track bearing surfaces and having grooves formed therein to receive said projections so as to be held in interlocked position with said blade in said blade opening, said projections and grooves being adapted to enter into or recede from such intertting position when said blade adjacent to said cam-track bearing surfaces is flexed outwardly from the normal plane of said blade and said member is given a rotative movement relative to said blade.

3. A device of the -class described comprising a blade having an area provided with a cam track opening and a flexible portion extending along a side of said opening, a flange of less length than said flexible portion projecting therefrom into the opening, and a cam track in the cam track openin'g and provided with a cam opening, said cam track having a grooved side portion slidably engaged with said flange and another side portion adjacent said grooved portion in contact with a corresponding side of the cam track opening and provided with a cam surface.

4. A device of the class described comprising a blade having an area provided with a cam track opening enclosed at its sides by flexible portions of the blade, flanges of less length than said portions projecting therefrom into the opening, a cam track comprising a frame having a periphery substantially matching that of the opening and enclosing a cam opening, said cam track being mounted in the cam track opening and having grooved side portions slidably engaging said flanges.

5. A device of the class described comprising a blade having an area provided with a cam track opening and a flexible portion extending along a side of said opening, a flange of less length than said flexible portion projecting therefrom into the opening and having an end spaced from the side of the opening adjoining said flexible portion, and a cam track having a, periphery substantially matching that of the cam track opening and mounted therein, said cam track being provided with a cam opening and having a grooved side portion slidably engaging said flange.

6. A device of the class described -comprising a blade having a plane area provided with a cam track opening enclosed at its sides by flexible portions of the blade, flanges of less length than said portions projecting therefrom into the opening, and a cam track comprising a frame enclosing a cam opening and having side portions thicker than said flanges and provided with grooves slidably engaging said fianges.

7. A device of the class described comprising a blade having an area provided with a cam track opening enclosed at its sides by flexible portions of said blade, flanges of less length than said portions projecting therefrom into the opening, and a, cam track comprising a frame enclosing a cam opening and having side portions slidably engaging said fianges.

IRVING CISSKI.

REFERENCES CITED UNITED STATES PATENTS Name Date Sontagh et al Dec. 15, 1936 Number 

